Question

4. A teacher believes that whatever he says in class has no effect on his students. Just as he's about to quit his profession, a statistician enters the room and suggests that the teacher design a study to test his assumption. The study will look at whether providing in-class feedback on homework assignments enhances classroom performance. The teacher wants to know whether providing feedback before or after returning the assignments is most useful. He's also interested in the most effective means of presenting the feedback: verbal presentation, written handout, or a summary on overheads. Ultimately, he'd like to identify the best approach for increasing test scores of the students. There are 12 classes available in the school for the experiment. Design an experiment that helps answer these questions. Be sure to identify the factors, the levels of the factors, the treatment groups, and the response variable. Comment on how the students will be assigned to the different treatment groups. Is it possible to use simple random assignment of all students? As much as possible, use diagrams instead of words to summarize your experimental design.

Answer 1

In order to design an experiment we will use the following design for the professor:

This is a two factor factorial experiment.

Here the factors are the 12 different classes and the Means of presenting the feedback.

Considering this, there are 12 x 3 = 36 different treatment groups and each treatment group has average scores of the students as the response variable measured before returning the assignment and measured after returning the assignment.

We will be assigning students by class and so it is not possible to do simple random assinment of students to the different treatment groups.

We will then be conducting an Analysis of Variance test for finding the best means of increasing the test scores of students.